Separable plug

ABSTRACT

An electrical plug is provided consisting of a body member loosely receiving the cable and a plug member separable from the body member and carrying the terminals for the cable and the prongs of the plug. When damaged, these prongs, or the body member as a whole, can readily be replaced and thereby discarding of the cable and plug assembly avoided. The body portion of the plug is of hollow, skirtlike structure, the cable being capable of being slid through the body to expose the terminals of the plug. The plug and body have interfitting parts forming pressure seals which render the interior of the body, and hence the terminals and conductors of the plug member, immune against the entry of water, moisture, or other foreign matter, particularly in portable equipment exposed to the weather.

United States Patent Savoca et al.

3,641,478 Feb. 8, 1972 [54] SEPARABLE PLUG 634,486 8/1936 Germany..............................339/63R [72] Inventors: Paul C. Savoca, Massapequa, N.Y.; P

I M nmary Examiner-Marvin A. Champion M y Norwalk Assistant Examiner-Lawrence J. Staab [73] Assignee: J. B. Nottingham 8: Co., lnc., New York, Attorney-Joseph Hirschmann ABSTRACT An electrical plug is provided consisting of a body member loosely receiving the cable and a plug member separable from the body member and carrying the terminals for the cable and the prongs of the plug. When damaged, these prongs, or the 1101 21/04 body member as a whole, can readily be replaced and thereby discarding of the cable and plug assembly avoided. The body portion of the plug is of hollow, skirtlike structure, the cable being capable of being slid through the body to expose the terminals of the plug. The plug and body have interfitting parts forming pressure seals which render the interior of the body, and hence the terminals and conductors of the plug member, immune against the entry of water, moisture, or other foreign matter, particularly in portable equipment exposed to the weather.

mm m we M Wm B 3, mS 33 6 m M W a WA am mmw W .wmc mm m e 9 H.mm mm a m ww..m mm 4 mmd W m "RD Y8 A Mu m mm we n u m nna 5m mr umn m 1111]] m 2 2 86 3 DD UUUU 3 63,801 4/1955 Franoe...................................339/l96 307,158 3/1929 Great Britain 4 Claims 3 Drawing Figures PNENWFW @191? 3.641.,AT8

INVI JN'I'OHS PAUL C. SAVOCA ANTHONY D. MARASCO n f' ATTORNEY SEPARABLE PLUG The present invention relates to electrical plugs, and particularly to plugs designed for use as connectors in circuits carrying high currents, as in welding circuits and the like, and especially to plugs and attached cables intended for use with portable apparatus which is exposed to the weather.

It is the general object of the invention to provide a plug of the character indicated and comprising a hollow body member and a separable plug member, the plug member carrying the prongs and the terminals connected with the conductors of the cable being protected against-the access of water, moisture, or other foreign matter by the body member, the two members being separable to expose the terminals for inspection and repair, or for the replacement of the entire plug member when damaged beyond repair.

Other objects of the invention are to provide a plug having an inner or plug member and an outer body member wherein the cable conductors are releasably connected to terminals embedded in a molded plug member, the cable being capable of being drawn through the body member as the plug member is forcibly pulled out of the body member to expose the terminal connections; to provide a two-part plug whose parts have a resilient O-ring seal in one part which is received in a corresponding peripheral groove in the other part to seal the interior of the body member against the entry of foreign matter; to provide a plug whose body member and plug member parts are roughly of complementary S-shaped outline at their adjacent ends, so that a double O-ring seal is formed by the assembled parts; and to provide a separable plug member which contains the terminals for connection to the cable conductors, and also the prongs which may be integral with the terminals and form an extension of the latter.

Other objects and advantages of the invention will appear from the detailed description thereof hereinafter.

in the prior constructions of heavy-duty plugs which are exposed to rain, snow and dampness, the effort has always been directed toward avoiding additional regions of accessibility of water, moisture and the like to the metallic conducting parts carried by the plug. This was particularly true in the case of heavy duty plugs, since these afforded a larger area for the entrance of water, moisture and the like, by reason of their relatively large dimensions and also by reason of the large torques exerted in handling, which would tend to cause separation at the interfitting faces of the parts of the plug when the latter was made of a plurality of parts. These factors made it appear inadvisable to make a plug of more than one part, so as to avoid an additional region or regions of juncture which would increase the opportunity for the entrance of water or moisture which would create the danger of corrosion or other deterioration and even short circuiting. For this reason, it has been the practice to mold the ends of the cable conductors together with the terminals and prongs to which they are connected, in a mass of natural or synthetic rubber, so that when the plug became damaged or worn, both the plug and its connecting cable, and also the molded connector at the other end of the cable, had to be discarded.

We have found that a plug can be manufactured which enables simple and inexpensive repair of the plug to be made, such as the replacement of the plug member part without loss of the connecting cable, by making the plug of two parts in such manner that the resulting interface between the parts does not create accessibility to water, moisture, or the like.

In accordance with the invention, the plug is formed of a hollow body part which normally houses the separable plug member proper, the latter having molded and embedded therein the terminals for the cable conductors, and carrying also the prongs connected to or integral with the terminals; while the electrical cable is slidably received within the body part, so that the plug member can be pulled out of the body member to enable the conductors of the cable to be disconnected from the terminals of a damaged or worn plug member, and connected to a replacement plug member.

A preferred embodiment of the invention is illustrated in the accompanying drawing wherein:

FIG. 1 is a view in perspective showing the improved plug with the conductors attached thereto, the plug and a portion of the cable being pulled through the hollow main body or skirtlike member of the plug;

FIG. 2 shows the plug in assembled condition and ready for use; while FIG. 3 is a partial section along the line 3-3 of FIG. 2.

Referring to the drawing, a three-conductor cable is shown at 10 which, if desired, may be surrounded by a protective wire netting 11 molded within the top portion 12a of the hollow skirtlike body 12 of Neoprene or other insulating elastomer. The cable 10 is axially movable within the body 12,

as indicated in FIG. 1, wherein it is shown as pulled through body 12. The three conductors are shown at l3, l4 and 15, and these are received in copper or brass terminals l6, 17, 18 and secured therein by setscrews 19. The terminals l6, l7 18 extend through an insulating member 20, the terminals extending through such member and beyond it, as indicated at 21. To the bottom ends of these terminals are connected, as by force fitting or screw threading, the prongs 22, 23, 24.

In accordance with the invention, the member 20 is separable from the body or skirtlike member 12, but is normally so connected therewith that the conductors l3, 14, 15 and the terminals l6, l7, 18 are protected against the entry of water, moisture, or other foreign matter. To this end, the member 20 is provided, at a short distance from its upper end, with a peripheral resilient and integral O-ring 25, while the'hollow body 12 is provided a short distance from its lower end with an inner peripheral groove 26, the dimensions of the ring 25 and groove 26 being such that the member 20 can be forcibly inserted within the body 12 by expansion of the bottom end portion of such body, as indicated in FIG. 3. As shown in the drawing, the members 12 and 20 for the three-prong plug are of triangular configuration in horizontal cross section, but other appropriate shapes can be employed, especially with variation in the number of prongs.

In order further to protect the inner region 27 against the entry of water or moisture, the member 20 is provided with a shoulder 27' a short distance below the ring 25, so as to form a peripheral groove 28 into which there fits the lower end portion 29 of the body 12, as can best be seen in FIG. 3. The outline of the bottom portion of the body 12 in cross section is roughly S-shaped, while the corresponding portion of the member 20 is similarly S-shaped, so that pressure contact between the bottom portion of body 12 and the upper portion of the member 20 is extended along substantially the whole length of the S-configuration. Additionally the parts can be so dimensioned that the upper edge 30 of the member 20 is engaged by the inner inclined wall 31 of the body 12.

The dimensions of the interengaging parts of the members 12 and 20 are so determined that the parts in their final positions are under tension or pressure to insure water and moisture tightness along successive areas. in particular, the outer dimension of the O-ring or bead 25 is slightly larger than the inner dimension of the groove 26 in the body member, so that some force will be required to assemble parts 12 and 20, with the result that contact between the O-ring and its seat in the groove 26 will be under some tension or pressure, which will insure the sealing effect desired.

As shown in FIGS. 1 and 2, the terminal extensions 21 may be provided with an enlarged peripheral ring 32 of brass or other conducting alloy to serve as a stop and also to cooperate with the face of the receptacle (not shown) to form a seal. As already indicated, the prongs 22, 23, 24 may be threaded and removably secured to the tapped extensions 21.

The uppermost portion of the plug member 20 is the inner surface of the member 12 being inclined to the outer surface of the plug member at an acute angle, that is, at a more acute angle to the horizontal than the outer surface of the upperspace separates the two surfaces. As the region of contact between the uppermost edge of the plug member 20 and the interior surface of the body member 12 is more or less a line contact, much less force is required either to separate or to assemble the two parts than would be the case if the two surfaces were both more or less cylindrical and in contact throughout their whole extents.

It should also be observed, with reference to what has been termed the approximately S-shaped region of contact 26, 27, 28 between the lowermost end of the member 12 and the portion of the plug member overlapped by it in FlG. 3, that the bead 25 of the plug member and the extension 27 of the base member project in opposite directions, so that upon assembly or disassembly'the force required to separate or cause them to interengage is in oppositedirections along the longitudinal axis of the plug and base members which facilitates such assemblyan'd disassembly.

As will be evident from the drawing, the cable is cylindri cal and fits snugly within the cylindrical opening in the part 120, so as to form a watertight seal, yet is slideable vertically, as viewed in the drawing, within the part 120. The plug part 20, as shown in FIG. 2, extends a considerable distance below the lower edge of the hollow body member 12 and is preferably of noncircular form, so that it can be readily gripped to effect connection or disconnection of the parts12 and 20.

It will be seen from the foregoing that, despite the fact that the plug is composed of two parts 12 and 20 which can be separated to replace the part 20 with its prongs 22, 23, 24 with a new such part, highly effective seals have been provided against the entrance of water or moisture into the interior of the hollow molded body 12. At the same time, the plug has been made easily repairable or replaceable, and great economy effected in contrast with the prior necessity of discarding the cable with its molded plug, in the event of damage thereto.

As shown in FIG. 3, the outer wall of the hollow base 12 is of decreasing thickness from the bottom toward the top, which makes the base more flexible and more readily expansible when the plug member 20 is force-fitted thereinto. It will also be noted from FIG. 3 that the outer wall of the upper portion of the plug member 20 is parallel to the central longitudinal axis of the plug and that the lowermost portion 29 of the wall of the base 12 is of reduced internal diameter so that it engages the inner vertical wall of the groove 28 under pressure. This construction enables the parts 12 and 20 to be separated and also to be assembled by hand in the field. This is aided by the fact that the uppermost portion of the plug member 20, as already mentioned, has only a line contact with the inner wall of the base 12, as indicated at 30, which renders such portion more easily compressible as the parts are separated or fitted together.

We claim:

1. An electrical plug comprising a flexible hollow insulating body having an opening at its top for receiving a multiconductor electric cable, and a separable plug member having electric terminals and interfitting with said body, said. plug member having prongs projecting therefrom and electrically connected to said terminals, the plug member being receivable within the hollow body and having a peripheral bead adjacent to its inner end, said bead having external dimensions greater than the internal dimensions of the bottom portion of the hollow body, the inner wall of the lower portion of the body being provided with a peripheral groove for snugly receiving the peripheral bead of the plug member, the outer diameter of the bead and the outermost diameter of the groove being so related that the bead is received in the groove under pressure when the plug member is forced into the interi or space of the body after attachment of the electrical conductors to its terminals to provide a water and moistureproof seal between the plug member and body, the plug member having a peripheral groove directly below its bead into which the bottom end portion of the body is received, with the inner surface of said bottom end portion in contact with the inner surface of said peripheral groove, so that an additional pressure seal therebetween is provided, the bottom end portion of the body snap ing into ition within the ripheral groove as the be passes sai portion when the p ug member is forced into the body, and wherein the outer wall of the upper portion of the plug member is parallel to the central longitudinal axis of such member, whereas the inner wall of the hollow body is inclined to such axis, so that the contact between the upper portion of the plug member and the inside of the hollow body is a substantially continuous line contact with a wedge-shaped space between the plug member and the hollow body.

2. A plug according to claim 1, wherein the peripheral groove of the plug member is directly below the bead, so that the outline of the outer surface of the bead forms, in cross section, an S-shaped configuration with the wall of the last-mentioned groove, while the inner surface of the bottom portion of the body has a complementarily S-shaped outline, whereby pressure sealing contact is provided between the body and plug member substantially along the whole length of the S- shaped surfaces.

3. A plug according to claim 2, wherein the upper portion of the wall of the plug member is of reduced transverse dimension to provide a shoulder a short distance below the bead, thereby forming the said peripheral groove into which the bottom end portion of the body fits in pressure contact, said shoulder providing an extended lower end of the S-shaped area of contact.

4. A plug according to claim 1, wherein the plug member is noncircular in transverse section and wherein the interior of the base is correspondingly shaped. 

1. An electrical plug comprising a flexible hollow insulating body having an opening at its top for receiving a multiconductor electric cable, and a separable plug member having electric terminals and interfitting with said body, said plug member having prongs projecting therefrom and electrically connected to said terminals, the plug member being receivable within the hollow body and having a peripheral bead adjacent to its inner end, said bead having external dimensions greater than the internal dimensions of the bottom portion of the hollow body, the inner wall of the lower portion of the body being provided with a peripheral groove for snugly receiving the peripheral bead of the plug member, the outer diameter of the bead and the outermost diameter of the groove being so related that the bead is received in the groove under pressure when the plug member is forced into the interior space of the body after attachment of the electrical conductors to its terminals to provide a water and moistureproof seal between the plug member and body, the plug member having a peripheral groove directly below its bead into which the bottom end portion of the body is received, with the inner surface of said bottom end portion in contact with the inner surface of said peripheral groove, so that an additional pressure seal therebetween is provided, the bottom end portion of the body snapping into position within the peripheral groove as the bead passes said portion when the plug member is forced into the body, and wherein the outer wall of the upper portion of the plug member is parallel to the central longitudinal axis of such member, whereas the inner wall of the hollow body is inclined to such axis, so that the contact between the upper portion of the plug member and the inside of the hollow body is a substantially continuous line contact with a wedge-shaped space between the plug member and the hollow body.
 2. A plug according to claim 1, wherein the peripheral groove of the plug member is directly below the bead, so that the outline of the outer surface of the bead forms, in cross section, an S-shaped configuration with the wall of the last-mentioned groove, while the inner surface of the bottom portion of the body has a complementarily S-shaped outline, whereby pressure sealing contact is provided between the body and plug member substantially along the whole length of the S-shaped surfaces.
 3. A plug according to claim 2, wherein the upper portion of the wall of the plug member is of reduced transverse dimension to provide a shoulder a short distance below the bead, thereby forming the said peripheral groove into which the bottom end portion of the body fits in pressure contact, said shoulder providing an extended lower end of the S-shaped area of contact.
 4. A plug according to claim 1, wherein the plug member is noncircular in transverse section and wherein the interior of the base is correspondingly shaped. 